Mr2 sw20 3s-gte idle swinging.

[Brett West]

Hi.

Idle was fine. But then changed the fuel pump, pressure regulator and injectors. (Sard 800cc.) Got everything else pretty much sorted but idle. When the engine is warmed up idle starts to swing and so does the afr. Things that smooth´s it out little is when i take the closed loop lambda off or make it run rich. i.e changing the fuel table or turning on a/c.

Have tryed changing the idle base positions and they don´t seem  to do much difference. Nor changing the gain tables.

Could i have vacuum leaks or something? Or could it be some sort ignition problem? (Haven´t touched the ignition times after the upgraded fuel components. Car was running smooth idle before upgrade.)

Suggestions?

[Simon]

Most likely fuel related.

As this is in theory the only change.

I would check injector dead times are correct and that master fuel has been adjusted to allow for the bigger injectors.

[Felix Kreysig]

At which idle rpm are you aiming? I've found it hard to get stable idle at rpms below 900 with almost stock cams, light flywheel and 850cc SARD injectors even with all idle control options turned on. Although overall AFRs stabilize at 14.7:1 I believe that due to a very unfavorable relation of injector dead time to total pulse time the individual afrs for each injection event fluctuate causing torque fluctuations. Using the idle ignition trim helped a lot.

The stock 3SGTE idle control valve is a story of its own.... if you haven't already, I'd suggest you dismantle an clean it properly as it is very prone to coking rendering it react very sluggish or getting stuck completely. That leads to over and undershooting pulsewith when using PID Closed loop regulation.